I have to 2nd the vote for Duane Allman and how few really know how much this man was so influential to the success of other artists working as a studio musician and - creating the Allman Bros. Band and playing a large role in the sucess of Clapton's Layla album - all at the age of 24 before his tragic death on a motor bike. Just to give you an idea, it was he that developed the intro riff to Layla, along with the slide parts. Except for the 1st 3 songs - he's all over that album.

Also, without question, the greatest electric slide player - maybe I'm partial..we all can appreciate the wonderfull modern day slide players like Derek Trucks, Sonny Landruff, Warren Haynes, etc. , but Duane wrote the book for all of them to study. Really amazing.. listen to "Filmore East" or "Atlanta Pop Festival".......left us all to early.......

As for the most influential guitarist I would say jimi hendrix, yea i'd think of different people influenced different styles, but hendrix just seems to be the choice of influence for most players. Of course other people like randy rhoads, and malmsteen did lot too.

i would have to say jimi hendrix is number one and under him falls the great Dimebag(from pantera for those of you who dont know who he is RIP) these are the two most influencial guitarist ever.. jimi and DimeBag took playing the guitar to another level.. .. now i know that people are going to say no to this that there are far better guitar players..but in my mind these are the two best...dont get me wrong there are some killer guitar players out there but the only problem is that they try to be so damn technical on there riffs and solos that it all sounds the same they always stay within the scale and modes and never think outside the box like jimi and dime did....these to guys would hit a note that would sound not right but bend the sh*t out of it and make it right...not many people play like that anymore..they all stay in the box and try to see who can play faster..its not all about being fast is about the feel and the passion of the guitar player that makes him great...that is why jimi and dime are the best...

Obviously your taste in music Genre will determine a lot who you would consider the most influential. For me it is Paul Simon. I never get bored with his albums because every song is an adventure in different techniques and sounds. KodaKrome, Mother and Child Reunion, sounds of Silence.

Almost impossible to answer this question unless a genre is included in the query, talking about the rock world most the names mentioned in this thread were and are influential but only if staying within the rock world, but the question was so broadly put that it refers to guitar players and that opens up the field to all the genres, we all know that Hendrix (one of my hero) can never play a Segovia piece and vice versa, although they both play the same instrument different skills are required to accommodate the two discipline or genre.

So who is the most influential guitar player? It depends onto what one likes to listen to.